Proton exchange membrane (PEM) fuel cells use electrocatalysts for the oxidation of hydrogen at the anode and reduction of oxygen in air at the cathode. Currently, platinum (Pt) supported on high surface area carbons is the preferred electrocatalyst for PEM fuel cell systems. However, a significant problem hindering large-scale implementation of PEM fuel cell technology is the loss of performance during extended operation and automotive cycling. Recent investigations of the deterioration of cell performance have revealed that a considerable part of the performance loss is due to the degradation of the electrocatalyst. Carbon has been considered as a favorable catalyst support owing to its low cost, good electron conductivity, high surface area, and chemical stability. Still, corrosion of carbon supports on the cathode electrodes of PEM fuel cells is emerging as a challenging issue for long-term stability of PEM type fuel cells.
Before mass-produced automotive fuel cell technology can be made practical, the oxidative instability of carbon, used as the catalyst support at the oxygen electrode, must be addressed. Among the methods being examined for prolonging the lifetime of the catalyst-support is the use of alternative support materials, such as electronically conductive titanium sub-oxides or coatings such as silicates to protect the carbon.